Mobile phones and other mobile devices include volume settings which allow the user to control the volume of various audio outputs including a ringer and notification volume. In many situations such as in the evening or when in a meeting or class, the user will turn off the volume of such audio outputs so that the phone will not output a disruptive sound when a phone call or notification is received. The user will often leave the phone in this muted state for extended periods of time.
When the volume is turned off, many phones provide an option to cause the phone to vibrate when an incoming phone call or message is received. However, if the user has turned off the volume, it is likely that the user is in a situation where he or she will not immediately check the phone in response to a vibration. For this reason, when the phone's volume is turned off, it can be difficult to notify the user of an emergency or urgent matter.